French Pat. No. 1,601,955 teaches use of a catalyst having the composition AO.sub.3 -B.sub.2 O.sub.5 -M.sub.2 O.sub.5 -N.sub.x O-R.sub.2 O wherein A is Cr, Mo, W or U; B is V or Nb; M is P, As, Sb or Bi, N is Cu, Ag, Fe, Co or Ni; R is Li, Na, K, Cs or Rb. Preferred composition is 15-55 atomic %A, 30-70% B, 0-15% M, 0.1-20% N, and 0-15% R.
The present invention is a result of a search for more efficient catalysts for use in the oxidation of four-carbon hydrocarbons to produce maleic anhydride.
The catalysts employed in the present invention are unexpectedly advantageous in the production of maleic anhydride from n-butane, n-butenes and 1,3-butadiene.